This weekend will get colder, as a reinforcing cold front drops Canadian air into the Sunshine State.

Temps will drop into the 30's with a freeze possible across the Nature Coast Sunday morning. A freeze is unlikely across most of Pinellas and Hillsborough, but colder pockets of interior Polk and Hillsborough may see freezing readings in wind protected areas by Monday morning.

It is rare to have a freeze in Tampa so late in the year. In fact, Tampa has yet to have a freeze this year; 38 degrees is the coldest reading so far this winter. The average last date for a freeze on record in Tampa occurred on March 5, 1893... just three years after weather data began being collected for the city.

So let's take a look at why the chance of snow is being entertained:

Click to enlarge

The first map above shows strong winds aloft, channeling out a trough across the eastern half of the country. This northerly flow is pulling down cold air from Canada.

What's going on at 18,000 feet is represented by this upper layer air map at 500 mb. It also shows a short wave causing lifting air. This may generate showers if moisture is present.

Not enough moisture exists over central or north Florida, but it could squeeze out showers from Venice southward Saturday night. The timing of max lift -- or what's called Omega -- is before the coldest air gets here.

So we are working with a mechanism to cause showers, but not enough of the moisture ingredient for precipitation and the timing is too soon.

What other factors could cause snow? Sometimes cold air over warmer Gulf waters can cause moisture to condense out of the air. A deck of marine stratus clouds should form with sprinkles over the Gulf and coastal areas Saturday night and Sunday morning. The mixed layer close to the water surface would melt anything frozen.

Click to enlarge

The lines on the map above show how far south the freeze line at 5000 feet drops into Florida by Sunday afternoon. It is unusual for the lines to be so far south and under normal circumstances, this would indicate 32-degree air reaching the ground.

But the winds will be gusting from the NW overnight and the boundary layer will keep the air too mixed for a significant freeze or snow. A flurry is possible... but highly unlikely, because of the dry air and insufficient freezing air close to the ground that would cause the flakes to melt.